1. Field
The following description relates to a scalable application service, and more particularly, to a scalable application service that is serviced in a network environment where there are various terminals.
2. Description of the Related Art
With development of information communication technologies, more various kinds of electronic devices are being developed. Also, along with rapid development of mobile communication technologies, various kinds of mobile electronic devices as well as fixed-type electronic devices are being introduced. In the case of a desktop computer which is a representative fixed-type electronic device, the kinds of products are more and more diversified with performance enhancement. Meanwhile, typical analog electronic devices (for example, television) are being digitalized, and other home and office electronics (for example, washing machine, refrigerator, air conditioner, facsimile, printer, etc.) are also combined with information communication technologies to thus have enhanced performance while being further diversified.
Diversification in kind of electronic devices is significant in mobile devices. For example, a laptop computer, a cellular phone, a MP3 player, a digital camera, a hand-held multimedia player, a navigations, an electronic dictionary, an E-book reader, a DMB receiver, etc. have been already developed and widely being utilized. Also, recently, a smart phone, a smart pad, a tablet PC, etc. have been newly introduced, and related industries are rapidly being expanded. Accordingly, such mobile devices are more and more diversified according to their purposes and performance.
Besides, some functions of such fixed-type and/or mobile electronic devices are integrated. For example, a camera function, a GPS function, a multimedia reproducing function, etc. are presently adopted in most of electronic devices, and accordingly applications based on these functions are installed in the electronic devices when they are manufactured, or implemented to be able to be installed in them as necessary. Particularly, most of the electronic devices have a communication function using a wired/wireless network.
However, most of such electronic devices use different platforms and different service framework environments, as well as having different characteristics or performance according to their dedicated functions, and users who utilize the electronic devices also may have different ages, different sexes, different preferences, etc. Also, an electronic device may be used under different use environments according to users' tastes, network environments, etc. In the case of a service, such as a multimedia streaming service and a web service, which provides multimedia content, studies into providing a scalable service in consideration of the unique characteristics (for example, terminal capability, a display size, a supportable resolution, an accessible network, etc.) of various terminals have been conducted.
Recently, with popularization of an IPTV service using the Internet, broadcasting services move from a unidirectional service of providing multimedia content to viewers to an interactive service, and service objects are also being diversified. Along with the trend, the IPTV service is trying to provide applications executable in various terminals, such as TV, a computer, a mobile terminal, as well as providing multimedia data, such as video, audio, images, etc.
Recently, a technical trial to provide a mobile IPTV service through a mobile communication network is being run. When a mobile IPTV service is realized, the IPTV service will be evaluated to an IP convergence service that can be supported in both wired and wireless networks. Particularly, since the mobile IPTV service will be able to be provided through all terminals having a communication function through a mobile communication network, the IPTV service is expected to be able to be supported for various terminals at the same time. Recently, studies into an IPTV service capable of providing multimedia content adaptively to various terminals using a multilayered video coding method, such as scalable video coding (SVC), etc. are being conducted.
However, SVC is a method of hierarchically encoding video content (moving images) to provide the video content to various terminals. Unlike this, an application service provides various contents including video, in the form of a program that is installed in and executable by a user terminal or an engine, such as JAVA, FLASH, etc., and the application service integrates a plurality of factors and/or conditions. When such an application program is reproduced, an application to which integrated factors and/or conditions are reflected can be represented on a GUI of a user terminal.
However, presently, application programs have been provided with a single format regardless of the kinds or characteristics of terminals so far, and standardization or studies into a method of providing application programs optimized for various terminals have not sufficiently been conducted. In other words, IPTV services developed so far have not considered the individual characteristics (for example, performance or display size) of terminals. For example, an application program that reproduces multimedia content, data, etc. provided through an IPTV service has fixed characteristics (for example, image quality, sound quality, security level, the kind or number of content configuring GUI, an accessible range, etc.), and does not provide a service adaptively in consideration of the individual characteristics of terminals. Accordingly, the application program cannot provide an application service optimized for the performance and specification of a specific terminal.
A method of providing an optimized application service in consideration of the performance specification of a terminal has been introduced in which a service provider creates and provides a plurality of formats for GUI in consideration of the performance specifications of various terminals. For example, when a user tries web browsing through a mobile device with a small size of display, a content provider, such as Naver, Daum, etc., enables the mobile terminal to access a web page created in advance for the mobile terminal in order to represent a web suitable for the mobile terminal. However, since the method should create various formats of content in advance and store them in a service server, a service provider had to cover high service cost. Furthermore, creating and storing GUIs optimized for all terminals with various characteristics is practically impossible.
Meanwhile, MPEG-21, which is an international standard defined by the Moving Picture Expert Group (MPEG), is in charge of multimedia framework standardization of a core technology and an integration technology required for electronic trading of digital content. MPEG-21 Digital Item Declaration (DID) (ISO/IEC 2100-2) defines how digital items are described and structurized, as the second part of the MPEG-21. Also, a MPEG-21 Digital Item Adaptation (DIA) (ISO/IEC 21000-7) framework includes a syntax and semantics tool capable of controlling digital items and optimizes the digital items according to users' tendencies and network environments.
However, since the syntax and semantics tool causes a large amount of overhead and have a complicated structure, it is not easy to use the syntax and semantics tool. The MPEG-21 defines a method of processing users' tendencies or information about a network environment, however, suggests no service method capable of applying user viewing state information in various terminal environments.